HE.net BGP origin attribute rewriting

Thu May 31 11:26:29 UTC 2012

On 31/05/2012 11:23, Daniel Suchy wrote:
> In my experience, there're not so many service providers
> doing that.

Plenty of providers do it.  IIWY, I would universally rewrite origin at
your ingress points to be the same; otherwise you'll find that providers
will merely use it as a means of influencing the bgp best path decision
algorithm so that they end up with more of your traffic, and can
consequently charge you more.  There are many useful ways to build a
multi-exit discrimination policy.  Using origin is not one of them, in my
opinion.

The problem is that origin is ranked one place higher than MED.  So if you
don't rewrite it, you are automatically giving your upstreams an inherent
means of strongly influencing the tie-breaking policy.  If this were an
attribute which actually meant something, then maybe there would be some
point in paying attention to it, but it conveys no useful information these
days.  IOW, it is completely pointless these days and you almost certainly
want to work the possibility of any upstream tweaking it.

Nick